a picture of it would help

there are a few ways hammering a socket over it

and i think halfords do reverse thread special too ???

not too sure how it works but it does

you can also drill it out that will take a while


hope you get it off in the end... i lost mine and they where mcgard HIGH SECURITY ONES ...BUT ..still had the id number of key

but had to send off to germany for 2 replacements